Veteran journalist and author Jacques Pauw is suing Piet Rampedi for R500 000.
Pauw confirmed Thursday on his Twitter page that Rampedi's lawyers received a summons after Rampedi failed to apologise or retract statement he made about Pauw on social media, calling him a child molester, liar and racist.
Rampedi is the assistant editor of the Sunday Independent.
"Rampedi's recent tweets about me are untrue, defamatory, extremely hurtful and damages my reputation as a journalist," Pauw said in a statement.
"I am not a liar, a racist or a paedophile. I have never touched any boys or any other children in Mozambique or any other place in the world. I am happily married and have been with my partner for 20 years."
He said Rampedi's molestation allegation was the reason for the defamation suit.
"Although I regard Rampedi's statements that I am a 'racist liar' as equally defamatory and untrue, it is the allegation that I am a paedophile, sex offender, molester of children and a criminal that are particularly hurtful.
"In order to expedite the case and steer away from long and protracted arguments, my legal team has suggested that we concentrate on the molesting statements. My rights in respect of the other accusations remain reserved."
Daily Maverick last month published an article by Pauw titled "Malema and Rampedi spin outlandish new 'rogue unit' narrative".
Rampedi quickly responded by calling Pauw a "liar" and "molester" on his social media pages.
He also alleged that Pauw lied in his 2017 book that the Guptas had bankrolled Rampedi's defunct African Times newspaper.
Pauw said: "It must be noted that Rampedi has 59 500 followers on Twitter. He has also repeated the allegation on Facebook. His damaging tweets were re-tweeted by hundreds of his followers, among others by EFF leader Julius Malema, who has 2.7 million followers, and two Members of Parliament.
"...his allegation have been outrageously insulting and offensive and I have generally been labelled as a paedophile and a sex offender. Many of Rampedi's followers have called me a criminal and called for my arrest."
Pauw also alleged Rampedi tried to get Pauw's publisher, NB Publishers, to retract a sentence in The President's Keepers where it was suggested that a newspaper Rampedi established, The African Times, was Gupta-funded.
Telephone calls to Rampedi went unanswered, but he later said on Twitter that his lawyers received the summons and he will defend the case "vigorously".
- Compiled by Tammy Petersen.